The invention provides a display device, a backlight module, a reflector plate and a manufacturing method of the reflector plate, and relates to the technical field of display. The manufacturing method comprises the steps that a nucleating agent and a foaming base material are mixed and added into a forming device, and the nucleating agent comprises a mesoporous material; supercritical gas is introduced into the forming device, and a foaming material is obtained through a forming process; and shaping the foaming material to obtain the reflecting film layer. According to the manufacturing method, the brightness can be improved under the condition that the energy consumption and the thickness are not increased.